Title

Authors

Date of this Version

5-2013

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A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy, Major: Chemistry, Under the Supervision of Professor Jody G. Redepenning. Lincoln, Nebraska: May, 2013

Copyright (c) 2013 Paul A. Goodman

Abstract

Electrochemical methods are an extremely diverse set of tools that can be applied to a large number of systems for quantitative, qualitative, and synthetic purposes. For the work described in this dissertation, electrochemical methods provided the basis for the analysis or fabrication of three unique systems.

Chapter 1 describes the analysis of carbon monoliths, produced by the pyrolysis of bovine bone, as electrodes in supercapacitor devices. After pyrolysis of the bone and subsequent removal of the hydroxyapatite support structure, via acid or ethylenediaminetetraacetic acid, a conductive carbon monolith that retains the macroscopic structure of the original bone remains. Analysis of the Raman spectra demonstrates that the carbon is similar to amorphous carbons. Electrochemical analysis shows that the monoliths have a specific capacitance of 134 ± 11 F/g in aqueous solutions of potassium nitrate and 108 ± 9 F/g in the ionic liquid 1-ethyl-3-methylimidizolium bis(trifluoromethylsulfonyl)imide.

Chapter 2 discusses the application of electrochemical methods to the analysis of the explosive triacetone triperoxide (TATP) in nonaqueous solutions. The E1/2 for the reduction of TATP at a glassy carbon electrode surface is -2.25 V vs. ferrocene/ferrocenium at a scan rate of 100 mV/s and is well described by a relatively slow two-electron reduction followed by a fast chemical transformation, as determined by bulk electrolysis and digital simulation experiments. It was found that the first reduction product of [tris(2-2’-bipyridine) ruthenium (III)] 2+ reacts with TATP in solution and shifts the reduction of the peroxide by +550 mV to -1.70 V vs. ferrocene.

Chapter 3 describes the electrochemical polymerization of aniline and pyrrole to bridge gaps of 50-200 nm between micropatterned electrodes. It was determined that polyaniline deposited from aqueous solutions of aniline containing sulfuric acid resulted in relatively uniform and stable bridges. Polypyrrole deposited from dry acetonitrile solutions of pyrrole containing tetrabutylammonium hexafluorophosphate also produced relatively uniform and stable bridges. When the oxidation states of the polymer bridges were switched from neutral to oxidized the resistance of the junctions decreased by 40% and 50% for polyaniline and polypyrrole, respectively. Junctions of this type could be used as the basis for sensor devices in the future.